Internal combustion engines often include techniques to improve various engine characteristics. But, an advantageous technique applied to one part of the engine may negatively affect other engine characteristics by introducing complexity and/or additional components.
One example technique for reducing nitrogen oxides (NOx) emissions from engine exhaust; formed when nitrogen and oxygen in the intake air is subjected to high combustion temperatures; is Exhaust Gas Recirculation (EGR) wherein a portion of cooled exhaust gas is recirculated back to the engine's combustion chamber(s) and mixed with the intake air. Another technique to increase power output is to add a turbocharger by capturing the power of exhaust gases to drive a compressor and increase the intake air density. However, including a turbocharger in an engine may make the management of possible undesirable exhaust byproducts more difficult.
U.S. Pat. No. 6,089,019 discloses an attempt to address the added complexity of combining a turbocharger with Exhaust Gas Recirculation (EGR). Specifically, in a turbocharged engine, the intake gas is typically at a higher pressure than the exhaust gas. But, in order to recirculate exhaust gas into the intake manifold, the exhaust gas must be at a higher pressure than the intake gas. The disclosure proposes placing a restrictor valve on the exhaust line upstream from the turbocharger, to restrict the flow of exhaust and increase the pressure of the exhaust gas. The increased pressure exhaust gas is provided to the inlet of an exhaust gas recirculation EGR valve actuatable independently of the actuation of the restrictor valve.
The inventors herein have recognized a number of problems with this approach. For one, there are other areas in an engine where untreated exhaust may be emitted into the atmosphere, for example areas in a turbocharged engine. Embodiments in accordance with the present disclosure may provide a way to reduce emissions that may otherwise leak from, or otherwise pass from, various moving components.
Embodiments in accordance with the present disclosure may provide an exhaust gas management arrangement for an engine. The exhaust gas management arrangement may include a port disposed to capture an exhaust gas leaked from a movable portion of an exhaust gas flow directing mechanism. The arrangement may also include a passage to direct the leaked exhaust gas to a crankcase of the engine. In this way, leaks may be controlled and instead be treated in accordance with preferred and/or established methods.
Some embodiments may provide a turbocharger wastegate for an engine including an enclosure in sealing engagement with a leakage possible portion of the wastegate. The wastegate may also include a fluid path from the enclosure to a positive crankcase ventilation (PCV) system to move exhaust gas leaked from the wastegate to a crankcase of the engine. The fluid path may include an oil return line for a bearing of the turbocharger. In this way, gasses leaked from the wastegate may be managed, and/or handled by the PCV system rather than be leaked to the atmosphere.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.